Class Notes (806,815)
Canada (492,451)
UOIT (1,636)
Biology (294)
BIOL 2020U (45)
Ani (45)

Refractory Period

2 Pages
Unlock Document

BIOL 2020U

Refractory Period  Represents a time during which the membrane cannot be depolarised again o During repolarisation and hyperpolarisation o Membrane is impermeable to Na+ ions / sodium ion channels closed o Sodium ions cannot enter axon o K+ ions move out as membrane is more permeable to K+ ions o Membrane becomes more negative than resting potential  Nerve impulses can only travel in one direction o Action potential can only depolarise the membrane in front o Membrane behind is recovering from refractory period (previous action potential)  Limits frequency with which neurones can transmit impulses Factors Affecting the Speed of Conductance: Myelin, Axon Diameter, Temperature  Impulses travel faster in myelinated neurones → SALTATORY CONDUCTION o Schwann cells prevent diffusion of ions o Flow of current between adjacent nodes of Ranvier o Thus, depolarisation only at nodes of Ranvier o Action potential jumps from node to node  Temp affects speed of conduction of impulses o Higher temp increases rate of diffusion of ions  Impulses faster in an axon with larger diameter o Small cells / large surface area:volume ratio / ion leakage weakens membrane o Myelin stops ion leakage \ diameter only important for unmyelinated neurones Synaptic Transmission  Synaptic cleft (gap) of 20μm separates two neurones at a synapse (junction of 2 neurones) o Presynaptic membrane is at the end of a neurone o Postsynaptic membrane is at the next neurone in the chain  Synaptic knob of a presynaptic neurone contains o Neurotransmitters in small vesicles o Mitochondria to produce ATP needed for neurotransmitter synthesis Aspects Of Synaptic Transmission  Unidirectional o Neurotransmitter always travels from pre- to p
More Less

Related notes for BIOL 2020U

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.